TWI609803B - Bumper beam and vehicle for vehicles - Google Patents

Description

Bumper beam and vehicle for vehicles

The present invention relates to a bumper beam for a vehicle. For further details, there are bumper beams for automobiles.

On the inside of the bumper of the vehicle, a bumper beam is provided. It is to ensure the safety of the vehicle by burdening the bumper beam during the conflict. In particular, a large amount of energy occurs in a car or the like in the event of a front collision. On the other hand, in recent years, from the viewpoint of reduction in CO ₂ and improvement in specific consumption of fuel, it is required to reduce the weight of the bumper beam. In order to reduce the weight of the bumper beam, it is necessary to thin the thickness of the bumper beam and increase the strength of the bumper beam.

In order to increase the strength of the bumper beam, there is a bumper beam which is reinforced by a reinforcing member (Japanese Patent Laid-Open No. Hei. 7-309184 (Patent Document 1), JP-A-6-328988 (Patent Document 2), and Japanese Laid-Open Patent Publication No. H6-171441 (Patent Document 3)).

In the bumper beam disclosed in Patent Document 1, a box-shaped space formed by a plurality of joined members is provided with a reinforcing structure. Pieces. The reinforcing member is along the front and rear direction of the vehicle. Thereby, the strength of the bumper beam is equivalent to that of the conventional bumper beam, and weight reduction and low cost can be achieved.

The bumper beam disclosed in Patent Document 2 has a box-shaped cross section and has a reinforcing member inside the box-shaped cross section. The reinforcing member is along the up and down direction of the vehicle. Therefore, when the load is applied in the front-rear direction of the vehicle, the deformation of the outer side of the upper wall portion and the lower wall portion is suppressed. Thereby, the strength of the bumper beam can be increased.

The bumper beam disclosed in Patent Document 3 is a cross section in which a hat-shaped press-formed product is combined to form a box shape, and a reinforcing member is provided in the internal space. The reinforcing member is along the up and down direction of the vehicle. Thereby, the strength of the bumper beam can be improved, and the deformation of the bumper beam is suppressed.

[Practical Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 7-309184

[Patent Document 2] Japanese Patent Laid-Open No. Hei 6-328988

[Patent Document 3] Japanese Patent Laid-Open No. Hei 6-114141

However, in the bumper beam of Patent Document 1, in the cross section seen from the side surface side of the vehicle, the compensation is arranged along the front-rear direction of the vehicle. Strong components. Therefore, when the load is a collision of the bumper beam, the reinforcing member is less likely to suppress the bending of the upper and lower wall portions. Therefore, it is difficult to increase the strength of the bumper beam.

In the bumper beam of Patent Document 2 and Patent Document 3, since the reinforcing member is disposed along the vertical direction of the vehicle in the cross section seen from the side surface side of the vehicle, deformation of the upper and lower wall portions is suppressed. As a result, the effect of suppressing the bending of the wall portion can be expected. However, since the surface of the load is easily deformed due to the load, the energy absorption efficiency of the bumper beam is limited.

An object of the present invention is to provide a bumper beam for a vehicle having high energy absorption efficiency.

A bumper beam according to an embodiment of the present invention includes a first member, a second member, and an intermediate plate. The first member includes a ceiling portion, two vertical wall portions, and two flange portions. The two vertical wall portions are connected to the respective sides of the ceiling portion. The two flange portions are connected to the two vertical wall portions. The second member has a plate shape and is joined to the two flange portions of the first member, and at least two flange portions are closed to each other. The intermediate plate is joined to the two vertical wall portions of the first member, and is disposed in parallel with the second member in a space formed by the first member and the second member. The second member of the first member and the second member is disposed toward the outer side of the vehicle.

The bumper beam of the present invention is a bumper beam for a vehicle having high energy absorption efficiency.

D1‧‧‧Interval between the second member and the middle plate

d2‧‧‧Interval between the slab and the midplane

h‧‧‧Interval between the second member and the slab

L‧‧‧ bumper beam length

P‧‧‧conflict load

X‧‧‧End of the vertical wall

1‧‧‧ bumper beam

2‧‧‧1st component

3‧‧‧2nd member

4‧‧‧ Medium board

4a, 4b‧‧‧ end

5‧‧‧Surface Department

5a, 5b‧‧‧ both sides

6‧‧‧ vertical wall

6a, 6b‧‧‧ vertical wall

7a, 7b‧‧‧Flange

8‧‧‧The difference in the vertical wall

10‧‧‧ bumper

Fig. 1 is a cross-sectional view showing a bumper beam of a first embodiment.

Figure 2A is a cross-sectional view of the bumper beam of Case 1.

Figure 2B is a cross-sectional view of the bumper beam of Case 2.

Fig. 3A is a view showing a deformation behavior of the bumper beam of the case 1, and shows an initial state.

Fig. 3B is a view showing a state performed from the state shown in Fig. 3A.

Fig. 3C is a view showing a state performed from the state shown in Fig. 3B.

Figure 4 is a load-bending line diagram for Case 1 and Case 2.

Fig. 5 is a view showing the relationship between the position of the intermediate plate and the energy absorption efficiency.

Fig. 6A is a view showing a deformation behavior of the bumper beam of the first embodiment, showing an initial state.

Fig. 6B is a view showing a state performed from the state shown in Fig. 6A.

Fig. 6C is a view showing a state performed from the state shown in Fig. 6B.

Fig. 6D is a view showing the state from the state shown in Fig. 6C Figure.

In the seventh drawing, the middle plate is a view showing the deformation behavior of the bumper beam of the case 2 to be added, and shows the initial state.

Fig. 7B is a view showing a state performed from the state shown in Fig. 7A.

Fig. 7C is a view showing a state performed from the state shown in Fig. 7B.

Fig. 7D is a view showing a state performed from the state shown in Fig. 7C.

Fig. 8 is a plan view of the bumper beam in which the concentrated load is the center of the load in the longitudinal direction.

Fig. 9 is a cross-sectional view of the bumper beam of the second embodiment as seen from above the vehicle.

Fig. 10 is a view showing an example of a joint portion between the vertical wall portion and the intermediate plate.

Fig. 11A is a cross-sectional view showing a bumper beam of an example of the present invention.

Fig. 11B is a cross-sectional view showing the bumper beam of Comparative Example 1.

Fig. 11C is a cross-sectional view showing the bumper beam of Comparative Example 2.

Fig. 12 is a load-bending amount line diagram of each of the bumper beams in the first embodiment.

Fig. 13 is a cross-sectional view showing the bumper beam of Comparative Example 3 and Comparative Example 4.

Fig. 14 is a load-bending amount line diagram of each of the bumper beams in the second embodiment.

Fig. 15 is a load-bending amount line diagram of each of the bumper beams in the third embodiment.

The bumper beam of the present embodiment includes a first member, a second member, and an intermediate plate. The first member includes a ceiling portion, two vertical wall portions, and two flange portions. The two vertical wall portions are connected to the respective sides of the ceiling portion. The two flange portions are connected to the two vertical wall portions. The second member has a plate shape and is joined to the two flange portions of the first member, and at least two flange portions are closed to each other. The intermediate plate is joined to the two vertical wall portions of the first member, and is disposed in parallel with the second member in a space formed by the first member and the second member. The second member of the first member and the second member is disposed toward the outer side of the vehicle.

Thereby, the maximum load allowed by the bumper beam is high, and the bending occurrence time is slow. Therefore, the energy absorption efficiency of the bumper beam is high. Here, the maximum allowable load of the bumper beam is the load applied to the bumper beam when the vertical wall portion of the bumper beam is bent (hereinafter referred to as "maximum allowable load"). Here, the energy absorption efficiency is a value obtained by dividing the energy absorbed by the bumper beam by the mass of the bumper beam when the collision load is applied.

In order to more fully exhibit an improvement in energy absorption efficiency, the ratio h1/h between the space h between the second member and the first member and the intermediate member d1 is 0 or more. 0.6 or less is preferred. More preferably, the interval h between the second member and the first member and the first member The ratio d1/h of the interval d1 between the member and the intermediate plate is 0 or more and 0.2 or less. Further, the interval h corresponds to the depth from the second member to the ceiling portion of the first member. The interval d1 is equivalent to the depth from the second member to the intermediate plate.

In the bumper beam described above, when the collision load is a second member placed on the outer side of the vehicle, the force in the tensile direction is generated in the ceiling portion of the first member disposed inside the vehicle. Therefore, cracks or breaks may occur in the roof portion. In order to cope with such a situation, when the entire length of the bumper beam is set to L, it is preferable to arrange the intermediate plate at least a part of the field of -0.2 × L or more and 0.2 × L or less from the center in the longitudinal direction of the bumper beam. More preferably, the intermediate plate is disposed at least a part of a field of -0.1 × L or more and 0.1 × L or less from the center in the longitudinal direction of the bumper beam. Therefore, since the vertical wall portion is bent before the crack occurs in the roof portion, the bumper beam is less likely to be broken. As a result, it is possible to suppress a large drop in energy absorption efficiency caused by breakage of the bumper beam.

In the above-described bumper beam, the first member and the intermediate plate are made of a metal plate, and the ratio t2/t1 of the thickness t1 of the first member and the thickness t2 of the intermediate plate is 0.7 or more, and preferably 1.0 or less. . Further, the ratio TS2/TS1 of the tensile strength TS1 of the first member and the tensile strength TS2 of the intermediate member is preferably 0.4 or more, and 1.0 or less.

In this case, since the strength of the intermediate plate is lower than that of the first member, the concentrated load is at the center in the longitudinal direction of the bumper beam, and since the vertical wall portion is bent before the crack occurs in the roof portion, Further suppressing the large energy absorption caused by the breakage of the bumper beam The decline in efficiency.

Preferably, the intermediate plate and the vertical wall portion are joined by welding. In particular, the end portion of the intermediate plate is bent, and it is preferable that the bent end portion and the vertical wall portion are joined in an overlapping state. In this case, when the end portion of the intermediate plate is bent toward the first member side, the intermediate plate is easily bent toward the second member.

Preferably, the first member and the second member are made of a steel sheet, and the tensile strength of the steel sheet is 1 GPa or more. Thereby, a bumper beam suitable for an automobile can be obtained.

The above bumper beam is applied to the vehicle. In this case, the vehicle is provided with the above-described bumper beam at the front or the rear of the vehicle. The second member of the bumper beam is disposed toward the outside of the vehicle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same symbols are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated. Further, the following example is a case where the bumper beam of the present embodiment is applied to a front bumper of an automobile.

[First Embodiment]

Fig. 1 is a cross-sectional view showing the bumper beam 1 of the first embodiment. In the first figure, the text "up" is displayed above the vehicle, and the text "front" is displayed in front of the vehicle. The same is true in the following figures. Referring to Fig. 1, the bumper beam 1 is disposed inside the bumper 10 of the vehicle. The bumper beam 1 includes a first member 2, a second member 3, and an intermediate plate 4. The bumper beam 1 of the first embodiment has a cross-sectional shape as shown in Fig. 1 and extends in the width direction of the vehicle.

The first member 2 includes a top plate portion 5, vertical wall portions 6a and 6b, and flange portions 7a and 7b. The respective ends of the two vertical wall portions 6a and 6b are connected to the respective side portions 5a and 5b of the ceiling portion 5. The other ends of the vertical wall portions 6a and 6b are connected to the flange portions 7a and 7b, respectively. The cross-sectional shape of the first member 2 is a hat-shaped open cross section. That is, the two flange portions 7a and 7b are open to each other. The first member 2 is, for example, a stamper formed of a metal plate.

The second member 3 is a plate-shaped member, for example, a metal plate is die-cut. A joint portion is provided between the second member 3 and the first member 2. Specifically, the second member 3 is joined to the flange portions 7a and 7b of the first member 2, and the flange portions 7a and 7b are closed from each other. That is, the first member 2 and the second member 3 joined to each other have a closed cross section.

The intermediate plate 4 is disposed in the space in which the first member 2 and the second member 3 are formed, and is disposed in parallel with the second member 3. A joint portion is provided between the intermediate plate 4 and the first member 2. Specifically, the end portions 4a and 4b of the intermediate plate 4 are bent at almost right angles, and are joined to the upper and lower vertical wall portions 6a and 6b, respectively. The end portions 4a, 4b of the intermediate plate 4 are disposed toward the ceiling portion 5. The intermediate plate 4 is, for example, a stamper formed of a metal plate. Such an intermediate plate 4 is a deformation that restrains the vertical wall portions 6a, 6b. Therefore, the vertical wall portions 6a and 6b are not easily bent. The middle plate 4 is not necessarily strictly parallel to the second member 3, and some inclination can be tolerated. This inclination is, for example, 10 or less.

In the intermediate plate 4, ribs may be provided along the vertical direction of the vehicle, or embossing may be applied. By the processing of these, the rigidity of the intermediate plate can be improved, so that the intermediate plate 4 can restrain the deformation of the vertical wall portions 6a and 6b. As a result, the vertical wall portions 6a and 6b are more difficult to bend, and it can be expected Increased energy absorption efficiency.

The bumper beam 1 is disposed such that the second member 3 faces the outside of the vehicle. For example, when the bumper beam 1 is applied as a bumper beam as a front bumper of the vehicle, the second member 3 is disposed toward the front of the vehicle. In the state in which the bumper beam 1 is placed on the vehicle, the roof portion 5, the second member 3, and the intermediate plate 4 of the first member 2 are in a posture that rises in the vertical direction of the vehicle. The vertical wall portions 6a and 6b of the first member 2 are vertically and upwardly oriented in the longitudinal direction of the vehicle. Thereby, the bumper beam 1 has a high energy absorption efficiency with respect to the collision in the front-rear direction. The following is detailed for this point.

When the bumper beam 1 is placed in a vehicle, two types of arrangements are considered. First, as shown in Fig. 1, the second member 3 is disposed toward the outside of the vehicle (hereinafter referred to as Case 1). Secondly, in the case of Patent Document 2 and Patent Document 3, the ceiling portion 5 of the first member 2 is disposed toward the outside of the vehicle (hereinafter referred to as Case 2). The present inventors have grasped the basic characteristics of the bumper beam, and in the case 1 and the case 2, the energy absorption efficiency was investigated by dynamic 3-point bending simulation analysis.

Fig. 2A and Fig. 2B are cross-sectional views showing a model of a bumper beam used in dynamic three-point bending simulation analysis. Among these figures, Fig. 2A shows the case of the bumper beam of the case 1, and Fig. 2B shows the case of the bumper beam of the case 2. The models in Case 1 and Case 2 do not have a midplane 4. Referring to Fig. 2A, in the case 1, the center of the longitudinal direction of the second member 3 is loaded with the entire direction of the sky in the vertical direction. The load P in the direction of the plate portion 5. With reference to FIG. 2B, in the case 2, the load P in the direction in which the entire area in the vertical direction faces the second member 3 is loaded in the center of the longitudinal direction of the roof portion 5. Moreover, the deformation behavior of the bumper beam is analyzed. At this time, the relationship between the load P and the amount of bending was examined for each bumper beam. Here, the amount of bending is the amount of bending of the portion where the load P is loaded. In the dynamic 3-point bending simulation analysis, the load load speed is set to 9 km/h, and the distance between the fulcrums is set to 800 mm. The analysis results are shown in Figures 3 and 4.

3A to 3C are views showing deformation behavior of the bumper beam of Case 1. The deformation of the bumper beam is performed in the order shown in Fig. 3, Fig. 3, and Fig. 3C. Referring to Figs. 3A to 3C, when the load P is the load on the second member 3, the compressive force is in the vicinity of the end portion X of the vertical wall portions 6a and 6b (hereinafter also referred to as the vertical wall portion 6). The length of the rod beam acts. Here, the compressive force is a force that compresses the two vertical wall portions 6 toward the longitudinal direction of the bumper beam. By the action of the compressive force, the end portion X on the second member 3 side of the vertical wall portion 6 moves toward the center in the vertical direction of the vehicle. As a result, the vertical wall portion 6 is deformed and eventually bends.

Fig. 4 is a load-bending line diagram of the bumper beam of Cases 1 and 2. The vertical axis is the display load and the horizontal axis is the display bending amount. In Fig. 4, the solid line shows the result of the bumper beam of Case 1, and the broken line shows the result of the bumper beam of Case 2. The load-bending line diagram shown in Fig. 4 is as follows. In Case 1, when the amount of bending is about 38 mm, it becomes the maximum load. The maximum load is about 62kN. The amount of bending is When it is about 38 mm or more, the vertical wall portion 6 is bent. In Case 2, when the amount of bending is about 42 mm, it becomes the maximum load. The maximum load is about 50kN. When the amount of bending is about 42 mm or more, the vertical wall portion 6 is bent. It can be seen that the maximum allowable load of Case 1 is higher than the maximum allowable load of Case 2. However, Case 1 is less curved than Case 2. In other words, case 1 is earlier than the case 2 when the bending occurs.

The energy absorbed by the bumper beam is equivalent to the integral value of the load-bend curve of Figure 4. Therefore, in order to improve the energy absorption efficiency of the bumper beam, it is only necessary to increase the maximum allowable load and to delay the occurrence of the bending time. The bumper beam of Case 1 is constructed with a maximum allowable load higher than Case 2. Here, the inventors of the present invention reviewed the time when the bending of the bumper beam of Case 1 was delayed and increased the energy absorption efficiency.

The bumper beam of Case 1 is as shown in Figs. 3A to 3C, because the end portion X is a compressive force acting on the vertical wall portion 6, and the vehicle is vertically oriented toward the bumper beam at an early stage. Since the center moves, the vertical wall portion 6 is deformed and bent. In other words, when the movement of the end portion X is suppressed, the vertical bending of the vertical wall portion 6 can be suppressed. Here, as shown in FIG. 1, the bumper beam 1 of the present embodiment is disposed in the space formed by the first member 2 and the second member 3, and the intermediate plate 4 is disposed in close proximity to the second member 3. The end portions 4a and 4b of the intermediate plate 4 are joined to the upper and lower vertical wall portions 6a and 6b, respectively. The intermediate plate 4 suppresses deformation of the vertical wall portion 6. Therefore, even if the end portion X moves, the vertical wall portion 6 is not easily deformed. That is, the vertical wall portion 6 is not easily bent. Thereby, the bending occurrence time of the bumper beam 1 is delayed. Further, since the bumper beam 1 is disposed so as to face the second member 3 toward the outside of the vehicle, the maximum allowable load of the bumper beam 1 is as high as that of the case 1. In other words, when the intermediate plate 4 is added to the bumper beam of the case 1 having a high maximum allowable load, the bending of the vertical wall portion 6 is suppressed, so that the bending occurrence time of the vertical wall portion 6 is delayed. Thereby, the energy absorption efficiency of the bumper beam 1 becomes high.

The position of the intermediate plate 4 is preferably close to the second member 3. Specifically, referring to Fig. 1, the ratio d1/h of the intermediate plate 4 is preferably 0 or more, and 0.6 or less. Here, h is an interval between the second member 3 and the first member 2 of the first member 2, and d1 is an interval between the second member 3 and the intermediate plate 4. This point will be described with reference to FIG. 5.

Fig. 5 is a view showing the energy absorption efficiency of the bumper beam which is different from the position d1/h of the position of the intermediate plate 4. The results shown in Fig. 5 were obtained by the same dynamic three-point bending simulation analysis described above. Each of the bumper beams having the ratio d1/h of the position of the intermediate plate 4 of the bumper beam shown in Fig. 1 was changed and simulated. The other analysis conditions are the same as the simulation analysis shown in FIGS. 3A to 3C and FIG. 4 described above. Referring to Fig. 5, the ratio d1/h of the energy absorption efficiency is a maximum at about 0.16. The ratio d1/h is larger than 0.16, and the energy absorption efficiency is decreased. The energy absorption efficiency without the middle plate 4 bumper beam is 0.44 kJ/kg (refer to the broken line in Fig. 5). When the ratio d1/h is larger than 0.65, the energy absorbing efficiency of the bumper beam having the intermediate plate 4 is an energy absorbing efficiency that is less than (below) without the intermediate plate 4 bumper beam. Therefore, the middle plate 4 is configured for the middle plate 4 The ratio d1/h is preferably 0 or more and 0.6 or less.

Further, the ratio d1/h of the position of the intermediate plate 4 is 0.2 or less, and the intermediate plate 4 and the second member 3 are in early contact during the load. Therefore, the bending of the second member 3 is restricted, and the movement of the end portion X of the vertical wall portion 6 shown in Fig. 3A is restricted. Therefore, the vertical wall portion 6 is less likely to be bent. In order to confirm this effect, the inventors of the present invention investigated the deformation behavior of the bumper beam having a ratio d1/h of 0.16 by dynamic three-point bending simulation analysis. The analysis conditions are the same as those of the simulation analysis shown in FIGS. 3A to 3C and FIG. 4 described above. The analysis results are shown in Fig. 6A to Fig. 6D.

Fig. 6 to Fig. 6D are diagrams showing deformation behavior of the bumper beam of the first embodiment. The deformation of the bumper beam having a ratio d1/h of 0.16 is performed in the order shown in Fig. 6, Fig. 6, Fig. 6, Fig. 6, and Fig. 6D. Referring to FIGS. 6A to 6D, when the load P is the load on the second member 3, since the compressive force acts on the vertical wall portion 6, the end portion X of the vertical wall portion 6 is a vehicle facing the bumper beam. Move in the center in the up and down direction. Since the intermediate plate 4 is joined to the vertical wall portion 6, the movement of the end portion X is compressed. At this time, the intermediate plate 4 is bent toward the second member 3 side. Therefore, the second member 3 and the intermediate plate 4 are in contact. When the intermediate plate 4 is in contact with the second member 3, since the bending of the second member 3 is restricted by the intermediate plate 4, the movement of the end portion X of the vertical wall portion 6 is also restricted. As a result, the bending of the vertical wall portion 6 is further suppressed. In other words, when the ratio d1/h is 0.2 or less, the bending of the vertical wall portion 6 is not caused only by the intermediate plate 4, but also by the contact between the intermediate plate 4 and the second member 3 as described above. effect. Therefore, the maximum allowable load of the bumper beam 1 is further improved.

Here, when the ratio d1/h is 0, the intermediate plate 4 comes into contact with the second member 3 before the load load P. In this case, the deformation of the second member 3 and the intermediate plate 4 is different. That is, the second member 3 and the intermediate plate 4 are integrally bent. Therefore, the energy absorption efficiency is lower than the case where the ratio d1/h is 0.16. Therefore, the preferred lower limit of the ratio d1/h is 0.1. However, the energy absorption efficiency of the bumper beam in the case where d1/h is 0 is higher than the energy absorption efficiency of the bumper beam without the intermediate plate 4. Therefore, the ratio d1/h is 0.

When the intermediate plate 4 is brought into contact with the second member 3 under a load, it is necessary to arrange the second member 3 toward the outside of the vehicle as in the case 1 shown in Fig. 2A. In other words, in the case 2 shown in FIG. 2B, when the ceiling portion 5 of the first member 2 is disposed toward the outside of the vehicle, the intermediate plate 4 is less likely to come into contact with the second member 3. In this regard, the inventors of the present invention investigated the deformation behavior of the bumper beam of the case 2 in which the middle plate was added by dynamic three-point bending simulation analysis. The analysis conditions are the same as those of the simulation analysis shown in FIGS. 3A to 3C and FIG. 4 described above. The analysis results are shown in Fig. 7A to Fig. 7D.

Fig. 7A to Fig. 7D are diagrams showing deformation behavior of the bumper beam of the case 2 in which the middle plate is added. That is, the roof portion 5 of the first member 2 is disposed toward the outside of the vehicle. The deformation of the bumper beam is performed in the order shown in Fig. 7A, Fig. 7B, Fig. 7C, and Fig. 7D. Referring to Figure 7A to Figure 7D, in Case 2 the load P is the load. In the case of the roof portion 5, the upper vertical wall portion 6a is curved in the upward direction of the vehicle, and the lower vertical wall portion 6b is curved in the downward direction of the vehicle. Therefore, the tensile force in the up and down direction of the vehicle acts on the intermediate plate 4. In this case, since the intermediate plate 4 is not easily bent, the top plate portion 5 and the intermediate plate 4 are not easily contacted. Therefore, as in Case 1, the contact of the load-bearing surface is not easily restricted by the contact of the intermediate plate 4 and the load-bearing surface. That is, in the case 2, it is difficult to suppress the bending of the vertical wall portion 6.

[Second Embodiment]

In the bumper beam of the first embodiment, since the intermediate plate can suppress the bending of the vertical wall portion, the energy absorption efficiency is high. However, when the concentrated load is excessively bent in the vertical wall portion, the load is generated in the center of the longitudinal direction of the bumper beam, and cracks occur in the roof portion of the first member on the back side before the vertical wall portion is bent. For example, even if the vertical wall portion is not bent, if the crack occurs in the roof portion, the energy absorption efficiency of the bumper beam is greatly lowered.

Fig. 8 is a plan view of the bumper beam in which the concentrated load is the center of the load in the longitudinal direction. In Fig. 8, the text "Right" is the right side of the display vehicle. The same is true in the following figures. With reference to Fig. 8, when the concentrated load P is at the center in the longitudinal direction of the bumper beam, the vicinity of the area where the concentrated load P is loaded is bent toward the rear of the vehicle (inward direction of the vehicle). At this time, since the roof portion 5 of the first member is disposed on the back side of the bumper beam, the force is received in the stretching direction (the left and right direction of the vehicle). If the force in this stretching direction is too large, cracks may occur in the roof portion 5. In short, if the bending of the vertical wall portion 6 is excessively suppressed, the longitudinal Before the bending of the wall portion 6, cracks occur in the roof portion 5. In particular, when the material strength of the bumper beam is high and the ductility is small, the case of the vertical wall of the first member is likely to cause cracks in the roof portion 5.

Here, in the bumper beam of the second embodiment, in order to suppress cracking of the roof portion, the position of the intermediate plate is limited to the longitudinal direction of the bumper beam. Specifically, the inventors of the present invention obtained the optimum position of the intermediate plate in the longitudinal direction of the bumper beam by the third embodiment to be described later. This point will be described with reference to Fig. 9.

Fig. 9 is a cross-sectional view of the bumper beam of the second embodiment as seen from above the vehicle. Referring to Fig. 9, the entire length of the bumper beam 1 is set to L, and an arbitrary distance from the center C in the longitudinal direction of the bumper beam 1 is set to L1. The middle plate 4 of the bumper beam 1 of the second embodiment is disposed in a central region of -L1 or more and L1 or less from the center C in the longitudinal direction of the bumper beam 1. Here, the intermediate plate 4 may be disposed in the entire area of the central area, and may be disposed in a part of the central area. The distance L1 is preferably 0.2 × L, more preferably 0.1 × L. Here, the length L1 is set to 0 in the center C in the longitudinal direction of the bumper beam, and the left-right direction of the vehicle is divided into a positive value and a negative value. In short, the intermediate plate is disposed from the center C in the longitudinal direction of the bumper beam to the side in the left-right direction of the vehicle to the area far from the distance L1.

By limiting the area in which the intermediate plate 4 is disposed to the central region in the longitudinal direction of the bumper beam, the end portion X of the vertical wall portion 6 of the field in which the intermediate plate is not disposed is easily directed toward the center of the bumper beam in the vertical direction of the vehicle. Move (refer to Figure 6A to Figure 6D). This result, the curvature of the vertical wall The time when the song occurred was advanced. Thereby, since the vertical wall portion is bent before the occurrence of the crack in the roof portion, it is possible to suppress a large drop in energy absorption efficiency caused by the breakage of the bumper beam.

When the excessive bending of the vertical wall portion 6 of the bumper beam is suppressed as described above, when the concentrated load P is at the center in the longitudinal direction of the bumper beam, cracks are likely to occur in the roof portion 5. In order to eliminate this problem, the thickness t2 of the intermediate plate 4 is preferably equal to or less than the thickness t1 of the first member 2. Since the bending occurrence time of the vertical wall portion 6 can be optimized, cracking in the roof portion 5 can be suppressed. Specifically, the ratio t2/t1 of the thickness t1 of the first member 2 and the thickness t2 of the intermediate plate 4 is preferably 0.7 or more, and preferably 1.0 or less. When the ratio t2/t1 is 0.7 or less, the strength of the intermediate plate 4 is low, so the vertical wall portion 6 is bent early. When the ratio of t2/t1 is larger than 1.0, the strength of the intermediate plate 4 is high. Therefore, when the concentrated load P is at the center in the longitudinal direction of the bumper beam, cracks are likely to occur in the roof portion 5. A preferred lower limit of the ratio t2/t1 is 0.8, and a preferred upper limit is 0.9.

Similarly to the above, in order to suppress the occurrence of cracks in the roof portion 5, the tensile strength TS2 of the intermediate plate 4 is preferably equal to or less than the tensile strength TS1 of the first member 2. Specifically, the ratio TS2/TS1 of the tensile strength TS1 of the first member 2 and the tensile strength TS2 of the intermediate plate 4 is preferably 0.4 or more, and 1.0 or less. When the ratio of TS2/TS1 is 0.4 or less, the strength of the intermediate plate 4 is low, so that the vertical wall portion 6 is bent early. When the ratio of TS2/TS1 is larger than 1.0, the strength of the intermediate plate 4 is high. Therefore, when the concentrated load P is the center of the longitudinal direction of the bumper beam, the end portion X of the vertical wall portion 6 is less likely to face the bumper beam. Center movement in the up and down direction (Fig. 6A~ 6 Figure D reference). As a result, cracks are likely to occur in the roof portion 5 before the vertical wall portion 6 is bent. A preferred lower limit of the ratio TS2/TS1 is 0.6, and a preferred upper limit is 0.8.

The joining of the intermediate plate 4 and the vertical wall portion 6 is, for example, welding. The welding method is, for example, spot welding, plug welding, arc welding, laser welding, or the like. However, the joining of the intermediate plate 4 and the vertical wall portion 6 is not limited to welding. The joining of the intermediate plate 4 and the vertical wall portion 6 may be mechanical joining. Mechanical joints are, for example, rivets, bolts and nuts, bolts, and the like. Further, the joining of the intermediate plate 4 and the vertical wall portion 6 may be an adhesive. The same applies to the joining of the first member 2 and the second member 3.

As described above, in the bumper beam of the present embodiment, the second member 3 is disposed toward the outer side of the vehicle. For example, as shown in Fig. 9, the bumper beam is bent in the longitudinal direction. In this case, the arc outside the curved bumper beam (the second member 3 side in FIG. 9) is disposed toward the outside of the vehicle. Further, the bumper beam is a crash box disposed inside the vehicle, and is attached to a front member or the like. Therefore, a mounting hole or the like is provided in the surface of the bumper beam inside the vehicle. In summary, even if the bumper beam is not attached to the vehicle, it can be determined that any of the first member or the second member of the bumper beam is disposed toward the outside of the vehicle.

Fig. 10 is a view showing an example of a joint portion between the vertical wall portion and the intermediate plate. Referring to Fig. 10, in the present embodiment, the step 8 for positioning the intermediate plate 4 may be provided in the vertical wall portion 6. As shown in Fig. 10, the size of the step 8 is about 0.5 mm to several mm. When the step 8 is 0.5 mm or less, the positioning of the intermediate plate 4 is not easy. If the step 8 is too large, the vertical wall portion 6 The rigidity of the bumper beam changes as it changes. In short, the step 8 of the vertical wall portion 6 is a range in which the deformation behavior of the bumper beam is not changed. By providing the step 8 in the vertical wall portion 6, the installation of the intermediate plate is easy, and it is easy to manufacture the bumper beam.

In the above embodiment, the case where the bumper beam is composed of a metal plate has been described. The metal plate is, for example, a steel plate, an aluminum plate, a titanium plate, a magnesium plate, a copper plate, a nickel plate or an alloy plate of these, a multi-layer metal plate, or the like.

In the case where the bumper beam of the present embodiment is applied to an automobile, the first member and the second member are preferably made of a steel sheet having a tensile strength of 1 GPa or more. In this case, the strength of the bumper beam can be further improved, and the safety of the vehicle body can be further improved.

In the above embodiment, the case where the bumper beam is provided at the front portion of the vehicle has been described. That is, the case where the bumper beam of the present embodiment is applied as the bumper beam of the front bumper of the automobile has been described. However, the bumper beam of the present embodiment is not limited to the bumper beam of the front bumper. The bumper beam of the present embodiment may be disposed at the rear of the vehicle. That is, the bumper beam of the present embodiment may be applied to a rear bumper or the like. In either case, the second member of the bumper beam is disposed toward the outside of the vehicle.

[Example 1]

In the first embodiment, the load beam simulation analysis was performed on the bumper beams having different configurations of the intermediate plates 4, and the energy absorption efficiency was investigated.

11A to 11C are cross-sectional views showing an analytical model of the bumper beam used in the first embodiment. Fig. 11A is a model showing Example 1 of the present invention and Example 2 of the present invention, FIG. 11B is a model showing Comparative Example 1, and FIG. 11C is a model showing Comparative Example 2. The ratio d1/h of the position of the intermediate plate 4 of the first embodiment of the present invention is set to 0.16, and the ratio d1/h of the position of the intermediate plate 4 of the second embodiment of the present invention is set to 0.5. In Comparative Example 1, a bumper beam without the intermediate plate 4 was assumed. In Comparative Example 2, it is assumed that the intermediate plate 4 is a bumper beam that is vertically disposed with respect to the second member 3.

For the sizes of the bumper beams, the width W1 of the vertical wall portion 6 of the first member 2 is set to 60 mm, the width W2 of the top plate portion 5 is set to 80 mm, and the width W3 of the second member 3 is set to 120 mm. . The load P is loaded toward the first member 2 at the center of the second member 3. The first member 2, the second member 3, and the intermediate plate 4 are steel sheets having a tensile strength of 1800 MPa and a plate thickness of 1.4 mm.

Fig. 12 is a load-bending curve of each of the bumper beams of the first embodiment. In Fig. 12, the solid line shows the result of Example 1 of the present invention, and the broken line shows Example 2 of the present invention. The 1-point lock line shows Comparative Example 1, and the 2-point lock line shows Comparative Example 2. Referring to Fig. 12, in the first embodiment of the present invention and the second embodiment of the present invention, the vertical wall portion 6 is not bent until the bending amount is about 38 mm. In Comparative Example 1 and Comparative Example 2, the vertical wall portion 6 was bent before the amount of bending reached 30 mm. In the inventive example 1, the maximum allowable load was about 73 kN, and in the inventive example 2, the maximum allowable load was about 62 kN. In Comparative Example 1, the maximum allowable load was about 45 kN, and in Comparative Example 2, the maximum allowable load was about 58 kN.

According to the analysis result of the first embodiment, the energy absorption efficiency of each bumper beam until the bending amount was 60 mm was calculated. The results are shown in Table 1.

The energy absorption efficiency of Example 1 of the present invention was 0.68 kJ/kg, and the energy absorption efficiency of Example 2 of the present invention was 0.56 kJ/kg. The energy absorption efficiency of Comparative Example 1 was 0.44 kJ/kg, and the energy absorption efficiency of Comparative Example 2 was 0.51 kJ/kg.

[Example 2]

In the second embodiment, the maximum allowable load of the bumper beam of the case 1 in which the intermediate plate 4 is added and the bumper beam of the case 2 to which the intermediate plate 4 is added are compared. In the second embodiment, the results of the second embodiment of the present invention in the first embodiment are cited. In the comparative example 3 and the comparative example 4, the intermediate plate 4 is placed on the bumper beam of the case 2, and the same load as in the first embodiment is performed. Load simulation analysis.

Fig. 13 is a cross-sectional view showing the bumper beam of the case 2 in which the intermediate plate 4 used in the second embodiment is added. Refer to Figure 13, related The ratio d2/h of the position of the intermediate plate 4 of Comparative Example 3 was set to 0.33, and the ratio d2/h of the position of the intermediate plate 4 of Comparative Example 4 was set to 0.5. The load P is applied to the center of the roof portion 5. Here, d2 is an interval between the ceiling portion 5 and the intermediate plate 4. That is, the interval d2 corresponds to the depth from the ceiling portion 5 to the intermediate plate 4.

Fig. 14 is a load-bending curve of each of the bumper beams of the second embodiment. For comparison, the results of Example 2 of the present invention conducted in Example 1 are also shown in Fig. 14. In Fig. 14, the solid line shows Example 2 of the present invention, the 1-point lock line shows Comparative Example 3, and the 2-point lock line shows Comparative Example 4. Referring to Fig. 14, in Comparative Example 3 and Comparative Example 4, when the amount of bending exceeds about 40 mm, the vertical wall portion 6 is bent. Further, the maximum allowable load of Comparative Example 3 and Comparative Example 4 was about 48 kN.

[Example 3]

In the third embodiment, load beam load simulation analysis is performed on the bumper beam defined in the field in which the intermediate plate 4 is disposed in the longitudinal direction, and the presence or absence of cracks in the roof portion is investigated. In the third embodiment, the width W1 of the vertical wall portion 6 of the first member 2 is set to 90 mm, the width W2 of the roof portion 5 is set to 80 mm, and the width W3 of the second member 3 is set to 120 mm. The distance L1 of the bumper beam 1 of the second embodiment shown in Fig. 9 was changed, and the same simulation analysis as in the first embodiment was performed.

Fig. 15 is a load-bending curve of each of the bumper beams of the third embodiment. In Fig. 15, the solid line is the result of displaying the bumper beam with a distance L1 of 0.06 x L. The dotted line is the display distance L1 is The result of a 0.2 x L bumper beam. The 1-point lock line is the result of displaying the bumper beam with a distance L1 of 0.5×L.

Referring to Fig. 15, in the bumper beam (dotted line) having a distance L1 of 0.2 × L, the amount of bending is about 100 mm, and cracking occurs in the roof portion. In the bumper beam (1 point lock line) having a distance L1 of 0.5 × L, the amount of bending is about 95 mm, and cracking occurs in the roof portion.

On the other hand, in the bumper beam (solid line) having a distance L1 of 0.06 × L, no crack occurred in the roof portion.

The embodiments of the present invention have been described above. However, the above-described embodiments are merely illustrative of the practice of the invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and implemented without departing from the spirit and scope of the invention.

1‧‧‧ bumper beam

2‧‧‧1st component

3‧‧‧2nd member

4‧‧‧ Medium board

4a‧‧‧End

4b‧‧‧End

5‧‧‧Surface Department

5a‧‧‧ both sides

5b‧‧‧ both sides

6‧‧‧ vertical wall

6a‧‧‧ vertical wall

6b‧‧‧ vertical wall

7a‧‧‧Flange

7b‧‧‧Flange

10‧‧‧ bumper

Claims (15)

A bumper beam for a vehicle includes: a first member including a ceiling portion; two vertical wall portions connected to each other on both side portions of the ceiling portion; and two adjacent vertical wall portions Two flange portions; and the second member is plate-shaped, joined to the two flange portions of the first member, and at least the two flange portions are closed to each other; and the intermediate plate is joined The two vertical wall portions of the first member are disposed in parallel with the second member in a space formed by the first member and the second member; and the first member and the second member are The second member is disposed toward the outside of the vehicle. The bumper beam for a vehicle according to the first aspect of the invention, wherein the distance h between the second member and the first member of the first member and the interval d1 between the second member and the intermediate plate are The ratio d1/h is 0 or more and 0.6 or less. The bumper beam for a vehicle according to the first aspect of the invention, wherein the distance h between the second member and the first member of the first member and the interval d1 between the second member and the intermediate plate are The ratio d1/h is 0 or more and 0.2 or less. For example, the bumper beam for a vehicle of claim 2 or 3, wherein When the entire length of the bumper beam is set to L, the intermediate plate is disposed at least in a portion from a center distance of the longitudinal direction of the bumper beam of -0.2 × L or more and 0.2 × L or less. The bumper beam for a vehicle according to the second or third aspect of the invention, wherein when the entire length of the bumper beam is set to L, the distance from the center of the longitudinal direction of the bumper beam is -0.1 × L or more, 0.1 × The at least one part of the field below L is configured with the aforementioned middle plate. The bumper beam for a vehicle according to any one of claims 1 to 3, wherein the first member and the intermediate plate are made of a metal plate, and a thickness t1 of the first member and a middle plate are used. The ratio t2/t1 of the plate thickness t2 is 0.7 or more and 1.0 or less. The bumper beam for a vehicle according to claim 4, wherein the first member and the intermediate plate are made of a metal plate, and a ratio of a thickness t1 of the first member to a thickness t2 of the intermediate plate T2/t1 is 0.7 or more and 1.0 or less. The bumper beam for a vehicle according to claim 5, wherein the first member and the intermediate plate are made of a metal plate, and a ratio of a thickness t1 of the first member to a thickness t2 of the intermediate plate. T2/t1 is 0.7 or more and 1.0 or less. For example, the vehicle warranty of any one of the patent scopes 1 to 3 In the bumper beam, the ratio TS2/TS1 of the tensile strength TS1 of the first member and the tensile strength TS2 of the intermediate plate is 0.4 or more and 1.0 or less. In the bumper beam for a vehicle according to the fourth aspect of the invention, the ratio TS2/TS1 of the tensile strength TS1 of the first member and the tensile strength TS2 of the intermediate plate is 0.4 or more and 1.0 or less. The vehicle bumper beam according to claim 5, wherein the ratio TS2/TS1 of the tensile strength TS1 of the first member and the tensile strength TS2 of the intermediate plate is 0.4 or more and 1.0 or less. The vehicle bumper beam according to claim 6, wherein the ratio TS2/TS1 of the tensile strength TS1 of the first member and the tensile strength TS2 of the intermediate plate is 0.4 or more and 1.0 or less. The bumper beam for a vehicle according to any one of claims 1 to 3, wherein the intermediate plate and the vertical wall portion are joined by welding. The bumper beam for a vehicle according to any one of claims 1 to 3, wherein the first member and the second member are made of a steel sheet, and the tensile strength of the steel sheet is 1 GPa or more. A vehicle having the first or the third part of the patent application scope In the vehicle bumper beam, the second member of the bumper beam is disposed toward the outside of the vehicle.